Add config to ignore PASV host

client.go

@@ -149,6 +149,11 @@ type Config struct {
 	// hung connections.
 	DisableEPSV bool
 
+	// Ignores the returned remote host IP for PASV connections. Some FTP Servers are
+	// behind NAT, and return their internal IPs. This ignores the IP portion of the
+	// PASV response, using the control connection's IP instead.
+	IgnoreHost bool
+
 	// For testing convenience.
 	stubResponses map[string]stubResponse
 }

persistent_connection.go

@@ -418,6 +418,20 @@ func (pconn *persistentConn) prepareDataConn() (func() (net.Conn, error), error)
 			return nil, err
 		}
 
+		// Some FTP servers are behind NAT themselves, and lie about their IP address.
+		if pconn.config.IgnoreHost {
+			pconn.debug("Ignoring PASV returned host %s", host)
+			_, remotePort, err := net.SplitHostPort(host)
+			if err != nil {
+				return nil, err
+			}
+			remoteHost, _, err := net.SplitHostPort(pconn.host)
+			if err != nil {
+				return nil, err
+			}
+			host = net.JoinHostPort(remoteHost, remotePort)
+		}
+
 		pconn.debug("opening data connection to %s", host)
 		dc, netErr := net.DialTimeout("tcp", host, pconn.config.Timeout)